Chromosome Numbers of Some North American Mirids (Heteroptera: Miridae)

Data are presented on the chromosome numbers (2n) of some eighty species of Miridae. The new information is combined with existing data on some Palearctic and Ethiopian species and discussed. From it, it is suggested that continued reference to 2n = 32A + X + Y as basic mirid karyotype should be avoided and that contrary to earlier suggestions, agmatoploidy rather than polyploidy is a more probable mechanism of numerical chromosomal change.